Ensuring the reliability and safety of pressure measurement instruments is important in any application, especially when you are dealing with challenging environmental conditions. Rating systems including the Ingress Protection (IP) and National Electrical Manufacturers Association (NEMA) were created to level the playing field for manufacturers by providing a standardized measure of an instrument's ability to withstand environmental challenges.
Understanding these rating systems can help you select the right equipment for your operational needs, ensuring instrument durability and safety.
With close to two centuries of experience as a global leader in pressure and temperature instrumentation, Ashcroft can help you understand why these ratings are important and what to look for when selecting pressure instruments for certain applications. When you're done reading, we will also share additional information that can help guide your selection process.
What is an Ingress Protection (IP) rating?
In a previous article, we explained that IP ratings were developed by the International Electrochemical Commission (IEC) to classify the level of protection that is provided by an instrument's enclosure. The 2-digit code indicates how well the enclosure can prevent the entry of solid objects like dust and debris, as well as liquids such as water, oil, or chemicals - all of which can lead to corrosion or other damage to the instrument. The higher the number, the higher the protection.
Figure 1. Example of an IP rating.
These ratings are crucial for determining the suitability of the pressure gauge to operate safely and efficiently when exposed to the elements. The chart below provides insight into the numeric system.
Figure 2. Ingress protection chart.
IP rating levels
IP ratings for both solids and liquids can be categorized into three levels:
- Low numbers: 0-4 (e.g., IP20, IP40) are suitable for indoor, controlled environments
- Moderate numbers: 4-5 (e.g., IP54, IP64) are more suitable for semi-protected environments, including automotive and HVAC where sensors encounter water splashes and dust
- High numbers: 6+ (e.g., IP65, IP67, IP69K) are best for use in challenging environments, such as marine, industrial and agricultural where equipment must endure outdoor conditions including water, dust and other contaminants.
Pressure gauge ratings can be found on the instrument datasheet. The Ashcroft® 1209 Pressure Gauge, for example, has a IP65. Using the chart above you can determine that this gauge has total protection against dust and protection against low-pressure water hitting it from any direction, which could be from a rainstorm.
Figure 3. Ashcroft®1209 Pressure Gauge IP rating specification.
What is a NEMA rating?
Similar to the IEC, the National Electrical Manufacturers Association (NEMA) also established standards to define the levels of protection provided by electrical enclosures against environmental conditions. Like IP ratings, NEMA evaluates whether electrical equipment can prevent elements such as dust, water, and corrosive agents from compromising the functionality and safety of an application.
The NEMA standards are widely recognized in North America, serving as a benchmark for manufacturers to design and test their products to meet environmental challenges. The following chart shows how NEMA classifies its ratings.
Figure 4. NEMA rating categories.
What are NEMA ratings for pressure gauges?
When it comes to classifying pressure gauges, NEMA ratings are often used to specify the suitability of these instruments for different environmental conditions. For instance,
- NEMA 4 enclosures are designed to protect against windblown dust and rain, splashing water, and hose-directed water, making them ideal for outdoor use
- NEMA 4X offers similar protection but with added resistance to corrosion, which is most beneficial in marine or chemical processing environments.
NEMA ratings can also be found on the pressure gauge datasheet. For example, the Ashcroft® T6500 Pressure Gauge has a NEMA 4X rating.
Figure 5. Ashcroft® T6500 Pressure Gauge IP rating specification.
Which rating is right for you?
Both IP and NEMA ratings serve the purpose of indicating the protective capabilities of enclosures, there are key differences and overlaps in their application. IP ratings are more focused on the ingress of solid particles and liquids, while NEMA ratings encompass a broader range of environmental factors, including corrosion resistance and construction quality. Understanding these distinctions is important for selecting the appropriate rating system based on the specific needs of your application.
Selecting between IP and NEMA ratings involves considering several factors, such as the specific environmental conditions the equipment will face, the regulatory standards applicable in the region, and the industry requirements.
Ready to learn more?
Protecting your measurement instruments from the elements is an important step in keeping your operation running safely and efficiently. Of course, there are other factors as well. If you would like more information about other considerations for selecting a pressure gauge, the following articles may be of interest:
- Six Reasons Pressure Gauges Fail Audits
- 10 Steps to Selecting Your Pressure Gauge
- What are the Advantages of Ashcroft Pressure Gauges
- NACE-Compliant Pressure Gauges for Sour Gas and Crude Oil Applications
- Why Pressure Gauges Need R110 Approval for CNG and LNG Applications
You can also contact us directly. Our industry experts can help answer your questions. In the meantime, check out our new Pressure Gauge Selection Tool, which will guide you through the process of finding the best gauge for your application.
